--- a/mobile/android/base/java/org/mozilla/gecko/toolbar/ToolbarEditText.java
+++ b/mobile/android/base/java/org/mozilla/gecko/toolbar/ToolbarEditText.java
@@ -423,16 +423,17 @@ public class ToolbarEditText extends Cus
     public InputConnection onCreateInputConnection(final EditorInfo outAttrs) {
         final InputConnection ic = super.onCreateInputConnection(outAttrs);
         if (ic == null) {
             return null;
         }
 
         if (isPrivateMode()) {
             outAttrs.inputType |= InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS;
+            outAttrs.imeOptions |= InputMethods.IME_FLAG_NO_PERSONALIZED_LEARNING;
         }
 
         return new InputConnectionWrapper(ic, false) {
             @Override
             public boolean deleteSurroundingText(final int beforeLength, final int afterLength) {
                 if (removeAutocomplete(getText())) {
                     // If we have autocomplete text, the cursor is at the boundary between
                     // regular and autocomplete text. So regardless of which direction we

--- a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/InputMethods.java
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/InputMethods.java
@@ -69,9 +69,12 @@ final public class InputMethods {
     public static boolean shouldCommitCharAsKey(String inputMethod) {
         return METHOD_HTC_TOUCH_INPUT.equals(inputMethod);
     }
 
     public static boolean needsRemoveAutocompleteHack(Context context) {
         String inputMethod = getCurrentInputMethod(context);
         return METHOD_SONY.equals(inputMethod);
     }
+
+    // TODO: Replace usages by definition in EditorInfoCompat once available (bug 1385726).
+    public static final int IME_FLAG_NO_PERSONALIZED_LEARNING = 0x1000000;
 }